We intend to do long term assessments of relationships between alcohol consumption, modifications in amino acids which are the precursors of neutrotransmitters, and 3 types of behavior i.e., depression, suicide and aggression in alcoholic patients. We have recently observed that, when compared with non-depressed alcoholics and controls, depressed alcoholics had significantly decreased ratios of plasma tryptophan to amino acids sharing with it the same transport carrier into the brain (tryptophan ratio). This ratio has been shown to predict the brain serotonin concentration. It is not presently known whether amino acid modifications disappear after a period of abstinence or persist. We will conduct studies aimed at elucidating this question. If biochemical changes persisted they could represent anomalies increasing the affected individuals' vulnerability to depression and should alert us to maintain heightened vigilance when treating these patients. We obtained preliminary data showing an association between a low tryptophan ratio depression and suicide attempts. Because associations had been found recently between suicidal and aggressive tendencies and because both types of behavior have been linked to lowered CSF levels of serotonin main metabolite, we studied relationships between amino acid modifications and manifestations of aggression in alcoholics. Patients who had exhibited violent behavior were observed to have tryptophan ratios lower than patients with no history of violence. Our studies need to be expanded and carried out in larger number of patients subjected to more extensive psychiatric assessments and to long term follow-up evaluations. The identification of biological factors contributing to depression or suicidal and aggressive behavior is important because the psychological and social costs of these types of behavior are great. In addition, it would be important to know that certain forms of mental disease would lend themselves to the relatively atraumatic therapy of amino acid supplementation.